Helicopter rotor



March'29, 1949. M, E, GLUHAREFF 2,465,681

HELICOPTER ROToR Filed Sept. 26, 1944 Patented Mar. 29,. 1949 HELICOPTER BOTOR Michael E. Gluhareif, Stratford, Conn., asaignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application September 26, 1944, Serial No. 555,8 17

4 claims. l

This invention relates to helicopters and more particularly to means for maintaining the several blades of a helicopter rotor in substantially symmetrical arrangement.

An object of the invention is the provision of hydraulic mechanism associated with the rotor blades of a helicopter to maintain the symmetrical arrangement of those blades.

Another object is to provide, in a helicopter having rotor blades hinged to a common axis for napping movements and having drag hinges, mechanism for maintaining the symmetrical arf rangement of the blade about their drag hinges.

Other objects and advantages will be apparent from the specication and claims, and from the accompanying drawing which illustrates what is now considered to be a preferred embodiment of the invention.

In the drawing,

Fig. 1 is a top elevation of the hub a helicopter sustaining rotor.

Fig. 2 is a side elevation with portions broken away of a portion of the helicopter of Fig. 1.

Fig. 3 is a detail showing an end view of the hydraulic cylinder and the connections thereto, and

Fig. 4 is a detail showing a section through the check valve.

The rotor hub is mounted on the upper end of shaft I8 which projects upwardly from the helicopter body (not shown) and the rotor may be driven in the usual manner by an engine supported in the helicopter body or by any other suitable means such as jet propulsion. The rotor hub comprises a disc I2, carried on the upper end of shaft I8. Bosses I4 and I8 are formed integral with the disc I2 and project upwardly therefrom. These bosses are apertured to receive a pin Il which forms the pin of the rotor-blade nappinghlnge. A link 24 is pivoted on pin I8 and extends outwardly from the rotor hub. I'he link 2l carries a pin 22 at its outer end. Pin 22 passes through one end of blade shank 24 and thus forms the pin of the drag hinge of the rotor blades. Rotor blades 28 are mounted on the other end of the blade shank 24.

A bracket 28 is mounted on each of the drag links 28 and, at its outer end carries a pivot 3l connecting it to a piston rod 32. The piston rods pass through cylinders indicated as 34, 38, and 38 and each piston rod carries a piston 48 dividing its associated cylinder into an inboard chamber 4I and an outboard chamber 43. Each piston 48 is provided with one or more restricted orliices 45 connecting the chambers 4I and 43. Each portion of (Cl. 17o-160.55)

2 cylinder is provided with a stumng box 42 at one end thereof and a stuillng box 44 at the other end thereof. Stuilng box 44 has lugs `46 which receive pins 48 to pivotally connect the cylinders 34, 36, and 38 with brackets 50, xed on blade Shanks 24.

The outboard chamber of each cylinder is connected to the inboard chamber of an adjacent cylinder. In the device illustrated outboard chamber 43 of cylinder 34 ls connected by means of flexible pipes 52 and 54 to the inboard chamber of cylinderr36 and, likewise, outboard chamber of cylinder 38 is connected by means of pipes 52 and 54 to the inboard chamber of cylinder 38, and outboard chamber of cylinder 38 is connected to the inboard chamber 4| of cylinder 34.

The pipes 52 and 54 are joined together to form the connections between the cylinders and are supported at the joint on the 1lnk28. A branch connection 58 is connected with the pipes 52 and 54 at the joint and leads to a reservoir 58 containing make-up oil for the chambers in the hydraulic cylinders 34, 3B, and 38. A check valve, generally indicated at 60 in the line 58, allows oil to now from the reservoir to the chambers in the cylinders but prevents return of oil from the cylinders to the reservoir. The reservoir is supported on the'hub I2 by support 82. Ifl desired, the valve 89 of the check valve 88 may be provided with or replaced by a small oriflce 6I to allow for oil expansion due to temperature.

As shown in Fig. 1, the rotor blades are symmetrically arranged about the hub I2, each being spaced from the others. Movement of any blade about its drag hinge 22 will destroy this symmetrical arrangement and tend to unbalance the rotor by placing more weight on one side of shaft I8 than on the other. In the construction shown, however, if one blade, say the blade shown on the top of the sheet, attempts to move forward, i. e., to the left, on its drag hinge, it will move its cylinder 34 down relative to the piston 40 and reduce the size of chamber 43, this will force oil out of the chamber 43 through pipes 82 and 84 to the inboard chamber of cylinder 38, thus moving cylinder 28 to the left and advancing its associated blade to the same extent that the blade associated with cylinder 34 advanced. This action, in turn, forcesA oil into the inboard chamber of cylinder 38 and, likewise, advances its associated blade. Hence, any attempt of one of the blades to move out of the symmetrical arrangement causes each of the other blades to move in the same direction and substantially an equal distance. This action ls the same for movement blades. A slight amount oi ilexibility is permitted by resilience of the connecting lines, and by restricted orices 4t in the pistons 40 which give the'pistons some shock-absorber characteristics.

This shock-absorber characteristic permits small amountsof relatively slow movement of one blade with respect to the others such as normally occurs. in the rotation of the blade due to diierences in drag of the blade as it rotates but acts to prevent any sudden large movement of.. one blade relative to the .others such as otherwise might be caused by sudden gusts or by a hard sidewise landing. The restricted orifices 45 also permit 4 oisaidonedevlcewithsaidonachamberotanv adjacent device so that movement c! 'the blade associated with said one device will cause substantially equal movement ot the adjacent blades.

3. In a helicopter rotor having movable blades. means for moving'one blade by movement oi' an adjacent blade comprising. interconnected hydraulic expansible chamber devices each includinga pair oi' expansible and contractible .chamthe return of the blades to a symmetrical-pattern after that pattern may have been temporarily disturbed. When orices 6I are utilized, the orir ces 45 may, if desired, be omitted.

From the above it will be appreciated that I l have provided a structure which will permit small amounts of relative movement of the bladeof a rotor but which, at the same time, acts to mainl tain the symmetrical arrangement of the blades and prevents any sudden disarrangexnent of the blade pattern.

It is to bel understood that the invention is not limited to the specific embodiment herein il.v lustrated and described, but may be used in other ways without departure from its spirit as denned by the following claims.

I claim: 1. Means i -connecting the severalblades of al multibladed rotating wing to synchronize movements thereof comprising, a pivot for each blade connecting said blade toa common support, a

`shoclr absorber comprising an expansible and contractible chamber device having two separate chambers, connected across each pivot.L one chamber expanding and the other contracting when the blade moves about its pivot, a restricted l orice connecting said chambers, and hydraulic means connecting said one chamber of each device with the other chamber of the next device.

2. In combination with a helicopter rotor having symmetrically spaced blades ymounted on drag hinges, a shock absorbing expansible chamber 1 device mounted across each said drag hinge and actuated by movement of its associated blade about said hinge, each said device comprising a pair of expansible and contractible chambers.

connected by a restricted orice, one of which `expands as the other contracts, hydraulic means connecting said one chamber of one device with said other chamber of an adjacent device. and hydraulic means connecting said other chamber bers. one device being operatively connected 'with each blade and actuated by movement of its associated blades whereby one chamber expands while the other chamber contracts. hydraulic means interconnecting the devices of adjacent blades, sothat expansion of one of the chambers of one device causes substantially equal expansion of the other chamber o! the adjacent device, a nuid reservoir connected with each interconnecting means for supplying additional fluid to keep the expansible chambers 'full oi' iluid and a restricted oriflce in each connection -to the reservoir.

4. In combination with a helicopter rotor having symmetrically spaced blades mounted on drag hinges, a shock absorbing device mounted across each of said drag hinges including a hydraulic cylinder pivotally connected to each of said blades for limited movement in the plane of rotation thereof and a cooperating piston having a connection to said rotorwhich is xedin the plane of rotation of said blade. each cylinder and piston forming a pair of expansible and contractible chambers, one of which expands as the other contracts, damper means comprising a restricted orirlce connecting the chambers of each device, means interconnecting said one chamber of each device with the other chamber of the next device, and a liquid reservoir mounted centrally of said hub including articulating connections to each of said interconnecting means.

' MICHAEL E. GLUHAREFF.

REFERENCES crrrzn l,

The following references are of record in the ille of this patent:

UNITED STATES PATENTS Oct. 5. 1943 

